Urinary dengue NS1 detection on Au-decorated ZnO nanowire platform.

Biodetection for non-invasive diagnostics of fluids, especially urine, remains a challenge to scientists due to low target concentrations. And biological complexes of the detection target may contain contaminants that also interfere with any assay. Dengue non-structural 1 protein (Dengue NS1) is an important biomarker for dengue hemorrhagic fever and dengue shock syndrome. Here, we developed an Au-decorated nanowire platform and applied it with a sandwich fluorophore-linked immunosorbent well plate assay (FLISA) to detect Dengue NS1 in urine. For the platform, we fabricated zinc oxide (ZnO) nanowires to provide a high surface area and then coated them with gold nanoparticles (ZnO/Au nanowires) to simply modify the Dengue NS1 antibody and enhance the fluorescence intensity. Our platform employs a sandwich FLISA that exhibits high sensitivity, specifically detecting Dengue NS1 with a limit of detection (LOD) of 1.35 pg/mL. This LOD was 4500-fold lower than the LOD of a commercially available kit for Dengue NS1 enzyme-linked immunosorbent assay. We believe that our ZnO/Au nanowire platform has the potential to revolutionize the field of non-invasive diagnostics for dengue.

The complete genome sequence of Kineothrix sp. MB12-C1, isolated from the feces of black soldier fly larvae.

Here, we present the complete genome sequence of Kineothrix sp. MB12-C1 (= BCRC 81406), isolated from the feces of black soldier fly (Hermetia illucens) larvae. The genome of strain MB12-C1 was chosen for further species classification and comparative genomic analysis.

Engineering Interface Defects and Interdiffusion at the Degenerate Conductive In2O3/Al2O3 Interface for Stable Electrodes in a Saline Solution.

A low-temperature Al2O3 deposition process provides a simplified method to form a conductive two-dimensional electron gas (2DEG) at the metal oxide/Al2O3 heterointerface. However, the impact of key factors of the interface defects and cation interdiffusion on the interface is still not well understood. Furthermore, there is still a blank space in terms of applications that go beyond the understanding of the interface's electrical conductivity. In this work, we carried out a systematic experimental study by oxygen plasma pretreatment and thermal annealing post-treatment to study the impact of interface defects and cation interdiffusion at the In2O3/Al2O3 interface on the electrical conductance, respectively. Combining the trends in electrical conductance with the structural characteristics, we found that building a sharp interface with a high concentration of interface defects provides a reliable approach to producing such a conductive interface. After applying this conductive interface as electrodes for fabricating a field-effect transistor (FET) device, we found that this interface electrode exhibited ultrastability in phosphate-buffered saline (PBS), a commonly used biological saline solution. This study provides new insights into the formation of conductive 2DEGs at metal oxide/Al2O3 interfaces and lays the foundation for further applications as electrodes in bioelectronic devices.

Integrated omic analysis provides insights into the molecular regulation of stress tolerance by partial root-zone drying in rice.

Partial root-zone drying (PRD) is an effective water-saving irrigation strategy that improves stress tolerance and facilitates efficient water use in several crops. It has long been considered that abscisic acid (ABA)-dependent drought resistance may be involved during partial root-zone drying. However, the molecular mechanisms underlying PRD-mediated stress tolerance remain unclear. It's hypothesized that other mechanisms might contribute to PRD-mediated drought tolerance. Here, rice seedlings were used as a research model and the complex transcriptomic and metabolic reprogramming processes were revealed during PRD, with several key genes involved in osmotic stress tolerance identified by using a combination of physiological, transcriptome, and metabolome analyses. Our results demonstrated that PRD induces transcriptomic alteration mainly in the roots but not in the leaves and adjusts several amino-acid and phytohormone metabolic pathways to maintain the balance between growth and stress response compared to the polyethylene glycol (PEG)-treated roots. Integrated analysis of the transcriptome and metabolome associated the co-expression modules with PRD-induced metabolic reprogramming. Several genes encoding the key transcription factors (TFs) were identified in these co-expression modules, highlighting several key TFs, including TCP19, WRI1a, ABF1, ABF2, DERF1, and TZF7, involved in nitrogen metabolism, lipid metabolism, ABA signaling, ethylene signaling, and stress regulation. Thus, our work presents the first evidence that molecular mechanisms other than ABA-mediated drought resistance are involved in PRD-mediated stress tolerance. Overall, our results provide new insights into PRD-mediated osmotic stress tolerance, clarify the molecular regulation induced by PRD, and identify genes useful for further improving water-use efficiency and/or stress tolerance in rice.

Mutation detection of urinary cell-free DNA via catch-and-release isolation on nanowires for liquid biopsy.

Cell-free DNA (cfDNA) and extracellular vesicles (EVs) are molecular biomarkers in liquid biopsies that can be applied for cancer detection, which are known to carry information on the necessary conditions for oncogenesis and cancer cell-specific activities after oncogenesis, respectively. Analyses for both cfDNA and EVs from the same body fluid can provide insights into screening and identifying the molecular subtypes of cancer; however, a major bottleneck is the lack of efficient and standardized techniques for the isolation of cfDNA and EVs from clinical specimens. Here, we achieved catch-and-release isolation by hydrogen bond-mediated binding of cfDNA in urine to zinc oxide (ZnO) nanowires, which also capture EVs by surface charge, and subsequently we identified genetic mutations in urinary cfDNA. The binding strength of hydrogen bonds between single-crystal ZnO nanowires and DNA was found to be equal to or larger than that of conventional hydrophobic interactions, suggesting the possibility of isolating trace amounts of cfDNA. Our results demonstrated that nanowire-based cancer screening assay can screen cancer and can identify the molecular subtypes of cancer in urine from brain tumor patients through EV analysis and cfDNA mutation analysis. We anticipate our method to be a starting point for more sophisticated diagnostic models of cancer screening and identification.

Topological insulator Bi2Se3 for highly sensitive, selective and anti-humidity gas sensors.

Chemiresistive gas sensors generally surfer from low selectivity, inferior anti-humidity, low response signal or signal-to-noise ratio, severely limiting the precise detection of chemical agents. Herein, we exploit high-performance gas sensors based on topological insulator Bi2Se3 that is distinguished from conventional materials by robust metallic surface states protected by time-reversal symmetry. In the presence of Se vacancies, Bi2Se3 nanosheets exhibit excellent gas sensing capability toward NO2, with a high response of 93% for 50 ppm and an ultralow theoretical limit of detection concentration about 0.06 ppb at room temperature. Remarkably, Bi2Se3 demonstrates ultrahigh anti-humidity interference characteristics, as the response with standard deviation of only 3.63% can be achieved in relative humidity range of 0-80%. These findings are supported by first-principles calculations, with analyses on adsorption energy and charge transfer directly revealing the anti-humidity and selectivity. This work may pave the way for implementation of exotic quantum states for intelligent applications.

Regulating Surface Wettability and Charge Density of Porous Carbon Particles by In Situ Growth of Polyaniline for Constructing an Efficient Electrical Percolation Network in Flow-Electrode Capacitive Deionization.

Both electrical conductivity and surface wettability are required for the selection of active carbon materials in flow-electrode capacitive deionization, while a trade-off exists between these two properties. In this work, a hybrid material with a thin layer of polyaniline (PANI) coating on activated carbon (AC/PANI) was successfully developed to retain excellent electrical conductivity and acquire good surface wettability. By adjusting the dosage of initiator, AC/PANI composites with different loading fractions of PANI were obtained. The electrochemical testing demonstrated that the AC/PANI composites have higher specific capacitance and lower ion diffusion resistance compared to pure AC, resulting in better desalinization performance. Specifically, with a feed concentration of 1600 mg/L, excellent adsorption capacity and high charge efficiency can be simultaneously achieved at 13.51 mg/g and 92.21%, respectively. Benefiting from the formation of a continuous electrical percolation network and reduced solid/liquid interfacial transport resistance, a 39% enhancement of average salt adsorption rate (from 0.54 to 0.75 µmol/min/cm2) was obtained.

A fitness training optimization system based on heart rate prediction under different activities.

Heart rate can be considered as an indicator of the exercise intensity in people's daily physical activities. Five heart rate zone theory is commonly adopted by individuals and professional athletes during their exercises and training. These heart rate zones are based upon percentages of people's maximal heart rate, which indicate different exercise intensities. The aim of paper is to propose an optimization training system based on dynamic heart rate prediction, which can predict people's heart rate under three different types of exercises: walking, running and rope jumping. The system can help people optimize their exercise by advising them to adjust the speed or workload to reach their predetermined training intensity under different activities. Four Long Short-Term Memory (LSTM) neural networks are deployed, one for human activity recognition (HAR) and three for heart rate prediction.

Tailoring ZnO nanowire crystallinity and morphology for label-free capturing of extracellular vesicles.

Zinc oxide (ZnO) nanowires have shown their potential in isolation of cancer-related biomolecules such as extracellular vesicles (EVs), RNAs, and DNAs for early diagnosis and therapeutic development of diseases. Since the function of inorganic nanowires changes depending on their morphology, previous studies have established strategies to control the morphology and have demonstrated attainment of improved properties for gas and organic compound detection, and for dye-sensitized solar cells and photoelectric conversion performance. Nevertheless, crystallinity and morphology of ZnO nanowires for capturing EVs, an important biomarker of cancer, have not yet been discussed. Here, we fabricated ZnO nanowires with different crystallinities and morphologies using an ammonia-assisted hydrothermal method, and we comprehensively analyzed the crystalline nature and oriented growth of the synthesized nanowires by X-ray diffraction and selected area electron diffraction using high resolution transmission electron microscopy. In evaluating the performance of label-free EV capture in a microfluidic device platform, we found both the crystallinity and morphology of ZnO nanowires affected EV capture efficiency. In particular, the zinc blende phase was identified as important for crystallinity, while increasing the nanowire density in the array was important for morphology to improve EV capture performance. These results highlighted that the key physicochemical properties of the ZnO nanowires were related to the EV capture performance.

Fabrication of a Robust In2O3 Nanolines FET Device as a Biosensor Platform.

Field-effect transistors (FETs) are attractive biosensor platforms for rapid and accurate detection of various analytes through surface immobilization of specific bio-receptors. Since it is difficult to maintain the electrical stability of semiconductors of sensing channel under physiological conditions for long periods, passivation by a stable metal oxide dielectric layer, such as Al2O3 or HfO2, is currently used as a common method to prevent damage. However, protecting the sensing channel by passivation has the disadvantage that the distance between the target and the conductive channel increases, and the sensing signal will be degraded by Debye shielding. Even though many efforts use semiconductor materials directly as channels for biosensors, the electrical stability of semiconductors in the physiological environments has rarely been studied. In this work, an In2O3 nanolines FET device with high robustness in artificial physiological solution of phosphate buffered saline (PBS) was fabricated and used as a platform for biosensors without employing passivation on the sensing channel. The FET device demonstrated reproducibility with an average threshold voltage (VTH) of 5.235 V and a standard deviation (SD) of 0.382 V. We tested the robustness of the In2O3 nanolines FET device in PBS solution and found that the device had a long-term electrical stability in PBS with more than 9 days' exposure. Finally, we demonstrated its applicability as a biosensor platform by testing the biosensing performance towards miR-21 targets after immobilizing the phosphonic acid terminated DNA probes. Since the surface immobilization of multiple bioreceptors is feasible, we demonstrate that the robust In2O3 FET device can be an excellent biosensor platform for biosensors.

ZnO/SiO2 core/shell nanowires for capturing CpG rich single-stranded DNAs.

Atomic layer deposition (ALD) is capable of providing an ultrathin layer on high-aspect ratio structures with good conformality and tunable film properties. In this research, we modified the surface of ZnO nanowires through ALD for the fabrication of a ZnO/SiO2 (core/shell) nanowire microfluidic device which we utilized for the capture of CpG-rich single-stranded DNAs (ssDNA). Structural changes of the nanowires while varying the number of ALD cycles were evaluated by statistical analysis and their relationship with the capture efficiency was investigated. We hypothesized that finding the optimum number of ALD cycles would be crucial to ensure adequate coating for successful tuning to the desired surface properties, besides promoting a sufficient trapping region with optimal spacing size for capturing the ssDNAs as the biomolecules traverse through the dispersed nanowires. Using the optimal condition, we achieved high capture efficiency of ssDNAs (86.7%) which showed good potential to be further extended for the analysis of CpG sites in cancer-related genes. This finding is beneficial to the future design of core/shell nanowires for capturing ssDNAs in biomedical applications.

Oxide Nanowire Microfluidic Devices for Capturing Single-stranded DNAs.

Since DNA analysis is the fundamental process for most applications in biomedical fields, capturing DNAs with high efficiency is important. Here, we used several oxide nanowire microfluidic devices to capture CpG-rich single-stranded DNAs (ssDNAs) in different pH solutions. All the oxide nanowires exhibited the highest capture efficiency around pH 7 with good capture efficiency shown by each metal oxide; ZnO/ZnO core/shell NWs (71.6%), ZnO/Al2O3 core/shell NWs (86.3%) and ZnO/SiO2 core/shell NWs (86.7%). ZnO/Al2O3 core/shell NWs showed the best performance for capturing ssDNAs under varying pH, which suggests its suitability for application in diverse biological fluids. The capturing efficiencies were attributed to the interactions from phosphate backbones and nucleobases of ssDNAs to each nanowire surface. This finding provides a useful platform for highly efficient capture of the target ssDNAs, and these results can be extended for future studies of cancer-related genes in complex biological fluids.

Photolithographically Constructed Single ZnO Nanowire Device and Its Ultraviolet Photoresponse.

A sparse ZnO nanowire array with aspect ratio of ca. 120 and growth rate of 1 µm/h was synthesized by controlling the density of seeds at the initial stage of nanowire growth. The spatially-separated nanowires were cut off from the growth substrate without breaking, and thus were useful in the construction of a single-nanowire device by photolithography. The device exhibited a linear current-voltage characteristic associated with ohmic contact between ZnO nanowire and electrodes. The device further demonstrated a reliable photoresponse with an IUV/Idark of ∼100 to ultraviolet light irradiation.

Synthesis of Monodispersedly Sized ZnO Nanowires from Randomly Sized Seeds.

We demonstrate the facile, rational synthesis of monodispersedly sized zinc oxide (ZnO) nanowires from randomly sized seeds by hydrothermal growth. Uniformly shaped nanowire tips constructed in ammonia-dominated alkaline conditions serve as a foundation for the subsequent formation of the monodisperse nanowires. By precisely controlling the sharp tip formation and the nucleation, our method substantially narrows the distribution of ZnO nanowire diameters from σ = 13.5 nm down to σ = 1.3 nm and controls their diameter by a completely bottom-up method, even initiating from randomly sized seeds. The proposed concept of sharp tip based monodisperse nanowires growth can be applied to the growth of diverse metal oxide nanowires and thus paves the way for bottom-up grown metal oxide nanowires-integrated nanodevices with a reliable performance.

Engineering Nanowire-Mediated Cell Lysis for Microbial Cell Identification.

Researchers have demonstrated great promise for inorganic nanowire use in analyzing cells or intracellular components. Although a stealth effect of nanowires toward cell surfaces allows preservation of the living intact cells when analyzing cells, as a completely opposite approach, the applicability to analyze intracellular components through disrupting cells is also central to understanding cellular information. However, the reported lysis strategy is insufficient for microbial cell lysis due to the cell robustness and wrong approach taken so far ( i. e., nanowire penetration into a cell membrane). Here we propose a nanowire-mediated lysis method for microbial cells by introducing the rupture approach initiated by cell membrane stretching; in other words, the nanowires do not penetrate the membrane, but rather they break the membrane between the nanowires. Entangling cells with the bacteria-compatible and flexible nanowires and membrane stretching of the entangled cells, induced by the shear force, play important roles for the nanowire-mediated lysis to Gram-positive and Gram-negative bacteria and yeast cells. Additionally, the nanowire-mediated lysis is readily compatible with the loop-mediated isothermal amplification (LAMP) method because the lysis is triggered by simply introducing the microbial cells. We show that an integration of the nanowire-mediated lysis with LAMP provides a means for a simple, rapid, one-step identification assay (just introducing a premixed solution into a device), resulting in visual chromatic identification of microbial cells. This approach allows researchers to develop a microfluidic analytical platform not only for microbial cell identification including drug- and heat-resistance cells but also for on-site detection without any contamination.

True Vapor-Liquid-Solid Process Suppresses Unintentional Carrier Doping of Single Crystalline Metal Oxide Nanowires.

Single crystalline nanowires composed of semiconducting metal oxides formed via a vapor-liquid-solid (VLS) process exhibit an electrical conductivity even without an intentional carrier doping, although these stoichiometric metal oxides are ideally insulators. Suppressing this unintentional doping effect has been a challenging issue not only for metal oxide nanowires but also for various nanostructured metal oxides toward their semiconductor applications. Here we demonstrate that a pure VLS crystal growth, which occurs only at liquid-solid (LS) interface, substantially suppresses an unintentional doping of single crystalline SnO2 nanowires. By strictly tailoring the crystal growth interface of VLS process, we found the gigantic difference of electrical conduction (up to 7 orders of magnitude) between nanowires formed only at LS interface and those formed at both LS and vapor-solid (VS) interfaces. On the basis of investigations with spatially resolved single nanowire electrical measurements, plane-view electron energy-loss spectroscopy, and molecular dynamics simulations, we reveal the gigantic suppression of unintentional carrier doping only for the crystal grown at LS interface due to the higher annealing effect at LS interface compared with that grown at VS interface. These implications will be a foundation to design the semiconducting properties of various nanostructured metal oxides.

Rational Concept for Reducing Growth Temperature in Vapor-Liquid-Solid Process of Metal Oxide Nanowires.

Vapor-liquid-solid (VLS) growth process of single crystalline metal oxide nanowires has proven the excellent ability to tailor the nanostructures. However, the VLS process of metal oxides in general requires relatively high growth temperatures, which essentially limits the application range. Here we propose a rational concept to reduce the growth temperature in VLS growth process of various metal oxide nanowires. Molecular dynamics (MD) simulation theoretically predicts that it is possible to reduce the growth temperature in VLS process of metal oxide nanowires by precisely controlling the vapor flux. This concept is based on the temperature dependent "material flux window" that the appropriate vapor flux for VLS process of nanowire growth decreases with decreasing the growth temperature. Experimentally, we found the applicability of this concept for reducing the growth temperature of VLS processes for various metal oxides including MgO, SnO2, and ZnO. In addition, we show the successful applications of this concept to VLS nanowire growths of metal oxides onto tin-doped indium oxide (ITO) glass and polyimide (PI) substrates, which require relatively low growth temperatures.

Tailoring Nucleation at Two Interfaces Enables Single Crystalline NiO Nanowires via Vapor-Liquid-Solid Route.

Here we show a rational strategy to fabricate single crystalline NiO nanowires via a vapor-liquid-solid (VLS) route, which essentially allows us to tailor the diameter and the spatial position. Our strategy is based on the suppression of the nucleation at vapor-solid (VS) interface, which promotes nucleation only at the liquid-solid (LS) interface. Manipulating both the supplied material fluxes (oxygen and metal) and the growth temperature enables enhancement of the nucleation only at the LS interface. Furthermore, this strategy allows us to reduce the growth temperature of single crystalline NiO nanowires down to 550 °C, which is the lowest growth temperature so far reported.